Fire-resistant hydraulic fluids



United States Patent Office 37159958 9 JRESETANT HYDRAULI FLUKDS Holzinger, Haid N1, assignors Inc, a corporation at Filed June 12, 1961, bier. No. 116,254 4 Claims. (Qi. 252-75) Nutley, Rudolph H. d, and Clarence Liddy, to ocony Mobil Git (Iompany,

No Drawing.

roved composition and particularly concerned oil emulsions useful as fire-resist- (1 their method This invention relates to an imp method of its preparati with improved wate ant hydraulic oils an of preparation.

Hydraulic systems are beingemploye extensively in industry to opera locations and wi liquids have be hydraulic systems; however, for these liquids have Various oils, such as miner in the past; however, systems cannot to mitting medium sin d metalworking oils an been found to 1 then find its way to combustion occurs. Hydraulic treating plants an caused serious acci ried in the prior art raulic oil that had the b long as these emulsions remain ormly dispersed throughout fine particles, th

sions have been t to provide a useful hyd low flammability. unbroken with the wa the oil in the form of remains high. Howeve e the resistance r, adequatestability in this res oi the emulsion has not been present in prior formulations. The water particles tend t and to settle to the lower part of pairing the fir o aggiomerate in clusters the reservoir, hereby imfluid remaining in the layer of clear oil e resistance of the In some case possessing no fire resistance wh more severe case droplets which eve of free water. on t of fire resistance,

esce into larger settle out and form a layer In addition toimpairment the latter condition is objectionable in ating system and may king parts and rapid of lubrication. it is es-' articles be dispersed tained. it is further all and uniformly corrosion tendency cause corrosion o wear of pump par sential, therefore, in the oil so that goo essential that the distributed throughout to a minimum an Several water-incess in that they have elimin ent in such operations. some success i ving parts to a consi ts due to lack that the water p d lubricity is ob the oil to keep ide the minimal amount oil emulsions have met with some sucated or mitigated fire hazards They have further met with have controlled wear of move' degree although they do not Patented Dec. 1, 1964 possess the antiwear properties of compounded mineral oils containing no water. It has been desired to improve the wear resistance of these water-in-oil emulsions up to the level of mineral oil and intensive investigations have been made to find a satisfactory additive system capable of maintaining highly stable water-in-oil emulsions with high wear resistance. Furthermore, in many instances, prior emulsion lubricants have been limited to operating hydraulic systems at low to moderate temperatures, e.g., at temperatures below 150 F. There are, however, many occasions where operating temperatures exceed 150 F. by a considerable margin. An example is the coal mining industry where mining machinery must operate in close quarters. In order to hold dimensions of hydraulic equipment to a minimum, capacity of the cooling system is restricted with the result that operating temperatures often exceed 150 F. In many cases, the system operates at 175 F. and in some cases even higher. While stability is important at these temperatures, it is even more important to prevent wear from being excessive at these elevated temperatures. 7

An object of this invention is to provide an improved composition for use as an hydraulic oil.

A further'object of this invention is to provide an improved oomposition having fire-resisting properties for use as an hydraulic oil. Y

A further object of this invention is to provide an improved stable water-in-oil emulsion having fire-resisting properties for use as an hydraulic oil.

A further object of this invention is to provide an improved stable water-in-oil emulsion having fire-resisting properties for use as an hydraulic oil and having stability under high temperature use conditions. 4

A further object of this invention is to provide an improved water-inil emulsion which causes minimum wear of moving parts even at elevated temperatures above 150 F.

A further object of this invention is to provide an improved water-in-oil emulsion which is free'from depositforming tendency.

These and other important objects will be made apparent in the ensuing detailed discussion of this invention. It has been found that a stable, fire-resistant water-inoil emulsion with good lubricating properties can be obtained by emulsifying up to 5 0 percent by volume of water with an oil of specified properties using an oil-soluble calcium petroleum sulphonate emulsifier in conjunction with critical amounts of potassium salts of low molecular weight aliphatic acids. It has also been found that certainadvantages can be obtained when critical amounts of potassium salts of low and high molecular weight aliphatic acids are used in combination.

Several'criteria are useful in evaluation of water-in-oil emulsions, particularly those intended for use as hydraulic fluids. Of first'importance is the lubricating ability of the product. Also of importance is stability of emulsion, particularly in use at high temperature. portance is the ability of the geneous throughout the test and not to form deposits which may tend to clog ports or screens.

A recognized test for lubricating capabilities, the socalled Vickers Pump Test, may be achieved by circulating the fluid by means of a Vickers pump, such as Vickers Vane Type Pump, Model V-lll-El (rated at 2 gal. per min), manufactured by Vickers Incorporated, of Detroit, Michigan. This is a positive displacement, vanetype hydraulic pump. The rotor, with twelve steel vanes in contact with a steel ring, turns at 1200 r.p.m. The twelve vanes and the ring are the test, and the weight of metal worn off durin is determined by difference. The pump test stand has a five gallon fluid reservoir and the fluid is circulated at 1000 p.s.i. pressure. A convenient duration of test is Likewise of imemulsion to remain homooils very frequently Vickers pump occurs encounter in service.

both on the vanes and Wear in the In order to evaluate deposit forming tendencies, strainers may be inserted in the system. .These can be examined at the end of the test run when the system is dismantled for inspection. At the same time, the reservoir can be examined for that a reserve alkalinity or composition, an oxidation inand the potassium salt of a low molecular weight fatty acid, either alone or in conjunction with the potassium salt of a high molecular weight fatty sidered to be indicative of the paraflinicity ing oil. The viscosity index of the oil to be used should be at least about 80.

purpose is Basic Calcium Petronate HMW L. Sonneborn Company, having a molecular weight of the order of 1000. It has been noted that free or reserve" alkalinity is essential. The above invert emulsifier contains about 40 percent active ingredient and has supplied by An oxidation inhibitor may be provided to prevent oxidative degeneration of the product in use which would level and then further increase of creased wear instead of reduction. Hence the broad range for this agent is about 0.01 to 1.0 percent by Weight of the total but the preferred range for this agent is about 0.025 to 0.25 percent by weight. The preferred acid ingredients of the soaps of this invention are those of saturated short chain fatty acids such as formic, acetic," propionic and butyric acids.

vary from 5:95 to :5.

The emulsions described herein are preferably prepared in the following manner. Two-thirds of the mineral oil is charged to a steam heated kettle equipped with mechanical agitation. The oil is heated to l50 F. and

the short chain fatty acid or mixture of short and long amount of alkali, e.g., potassium hydroxide, an equal quantity of water. The materials are mixed for an additional 15 minutes to neutralize the acids; the temperature is then raised to 190 F. When the temperature reaches 190 F., the calcium petroleum sulphonate is added and the temperature is raised to 260 F. The batch is maintained at this temperature for 5-10 minutes and the batch is then quenched immediately by adding the remainder of the mineral oil. The oxidation inhibitor is added and the temperature adjusted to 185 F. In a separate kettle, the required amount of water is heated to 175185 F. and slowly added to the oil mixture in the first kettle with vigorous agitation. Finally, the emulsion is passed through a colloid mill or homogenizer to obtain the finished emulsion of uniform, small particle size.

It has been found that when small amounts of potassium soaps of long chain fatty acids are included in the formulation the wear decreases. However, when the amounts of these agents are increased, the viscosity of the chain fatty acids have a tendency to form undesirable deposits on screens and strainers as well as internal reservoir surfaces. We have now found that these shortcomings can be eliminated by substituting potassium soaps The improvements indicated are illustrated in Table I hereinbelow.

TABLE I Results of Vickers Pump Tests [100 hours at 170-175 F. and 1,000 p.s.i.]

Percent by Weight Example No 1 2 3 4 5 6 7 8 Basic Calcium Petronate HMW 2. 5 2. 5 2. 5 2. 5 2. 5 2. 5 2. 5 2. 5 Agerite Stalite 0. 5 0.5 0. 5 0. 5 0.5 0.5 0.5 0. 4- Base Oil ,108 S.U.S. @100 F., Viscosity Index 95 57 0 56. 8 56. 91 56. 82 56. 82 56. 51 56. 86 56. 69 Potassium Stearate 0. 2 0.13 Potassium Acetate 0.09 a 0. 18 9 0.18 49 0. 18 Ca Acetate (Anhydrous) 2 0. 14 Water 40. 0 40. 0 40. 0 40. 0 40. 0 40. 0 40. 0 40. 0

Total Wear, mg 308 50 50 70 86 217 207 43 Vane Wear, mg.-- 19 23 9 10 13 5 70 7 Ring Wear, mg 289 27 41 60 73 212 197 36 Roughness Rating VanesL 1 1 1 1 1 1 3 1-2 Roughness Rating Bin 3 1 1-2 2-3 1-2 1-2 1-2 Reservoir Deposits None None None None None None None 1 Prepared from HFA 405 (Hydrogenated Animal Fatty Acid) ,essentially a commercial stearic acid.

2 Equivalent to 0.11 Glacial Acetic Acid.

3 Ratings: 1=Excellent; 2=Good; 3=Fair; 4=Poor.

4 Moderately Heavy.

Example No. l of Table I shows the high wear charactcristic of compositions not containing the antiwear agents.

Example No. 2 illustrates previous findings, namely, the

eifeotiveness of potassium stearate in reducing total wear from 308 mg. to 50mg. Example No. 3 demonstrates that an equal Wear reduction can be accomplished by the use of potassium acetate. It will be noted, however, that less than one-half the amount of additive is needed to obtain the same wear reduction. In other words, potassium acetate is at least twice as elfective as potassium stearate. It will also be noted that in Example No. 2, when using potassium stearate, wear is about evenly divided between vanes and ring (23 and 27 mg. respectively). In contrast, the use of potassium acetate has shifted a large portion of the wear from the critical vanes to the much less critical ring. Moreover, potassium acetate provides a further important improvement over potassium stearate in that it eliminates the reservoir deposits characteristic of the latter.

Examples No. 3 and No. 4 are identical in composition, both employing twice the amount of potassium acetate shown in No. 2. Total wear figures for No. 3 and No. 4, which are in fairly good agreement (70 and 86 mg., respectively) demonstarte that an increase in concentration does not result in further reduction of wear but instead causes a slight increase in wear, in the particular composition employed. This is shown also in Example 6. In-

crease in concentration of potassium acetate to 0.49% by weight causes a drastic increase in ring wear (212 mg), although vane wear remains remarkably low.

While it is thus possible to replace all of the potassium stearate by potassium acetate, it may be desirable to use the latter as a partial replacement only. One of the advantages that can be gained by the latter technique is that the formulator is enabled to balance the composition so as to distribute thetotalwear between the two rubbing surfaces in accordance with the design of the pump while retaining low over-all wear. Combinations of soaps of short and long chain fatty acids also have been found useful as a means of controlling emulsion viscosity since long chain fatty acid soaps .tend to increase viscosity whereas short chain acids tend to decrease it. Thus important advantages accrue from the use of such combinations which cannot be gained when either type of antiwear agent is used alone. y

In Example N0. 7, shown in Table I, calcium acetate is used as the antiwear agent. wear is but slightly less than that shown in Example 1 containing no antiwear agent. Moreover, wear has again shifted to the more critical vanes, with a weight loss of 70 mg. as compared to 19 mg. in No. 1. Although the It will be noted that total amount of calcium acetate is equivalent to the amount of potassium acetate used in Example 4, its effect on wear characteristics of the fluid is in no way comparable to the latter. Example No.8 shows the synergistic action of potassium stea-rate and potassium acetate.

j The radical difference in antiwear eiiects between the calcium and potassium soaps of short chain fatty acids is surprising. Calcium acetate is widely used in lubricating compositions of various kinds as an antiwear agent. However, it was found totally ineffective in the system under consideration when used in the concentration range here contemplated. On the other hand, we have found quite unexpectedly that potassium acetate, when used in relatively low concentrations, produces a drastic reduction of wear. This difference could not have been predicted from .priorknowledge, running quite contrary to what the prior art indicated.

The invention has been amply illustrated in the detailed discussion of the invention. These examples are given, however, only to illustrate the invention and are not intended as limitations. The only limitations intended are found in the following claims.

We claim:

1. A composition for use as hydraulic fluid consisting essentially of a water-in-oil emulsion, the water content of said emulsion, being about 10-50 percent by weight, the oil having a viscosity of about -400 Saybolt Universal seconds at 100 F. and a viscosity index of at least 80, about .25-6.00 percent by weight of oil-soluble calcium petroleum sulphonate having a molecular weight of at least 975, the calcium petroleum sulphonate having a minimum alkalinity equivalent to about 20-25 mg. of potassium hydroxide per gram of sulphonate as supplied, and about 0.011 to 1.0 percent by weight of a potassium salt of a saturated straight-chain fatty acid having a carbon chain length of C -C whereby a stable emulson is provided which effects minimum wear.

2. A composition for use as hydraulic fluid consisting essentially of a water-in-oil emulson, the water content of said emulsion being about 10-50 percent by weight, the oil having a viscosity of about 100-400 Saybolt Universal seconds at 100 F. and a viscosity index of at least 80, about 0.25-6.00 percent by weight of oil-soluble calcium petroleum sulphonate having a molecular weight of at least 975, the calcium petroleum sulphonate having a minimum alkalinity equivalent to about 20-25 mg. of potassium hydroxide per gram of sulphonate as supplied,

and about 0.01 to 1.0 percent by weight of potassium I 7 essentially of a water-in-oil emulsion, the Water content of said emulsion being about 1050 percent by weight, the oil having a viscosity of about 100-400 Saybolt Universal seconds at 100 F. and a viscosity index of at least 80, about 0.25-6.00 percent by weight of oil-soluble calcium petroleum sulphonate having a molecular weight of at least 975, the calcium petroleum sulphonate having a minimum alkalinity equivalent to about 20-25 mg. of potassium hydroxide per gram of sulphonate as supplied, about 0.01 to 1.0 percent by weight of a potassium salt of a saturated straight-chain fatty acid having a carbon chain length of C -C and about 0.02-1.49 by Weight of potassium stearate, the ratio of the potassium salt of the C -C saturated straigh-chain fatty acid to potassium stearate being from 5:95 to 95:5, whereby a stable emulsion is provided which effects minimum wear.

4. A composition for use as hydraulic fluid consisting essentially of a water-in-oil emulsion, the water content of said emulsion being about 25-45 percent by weight,

the oil having a viscosity of about 100400 Saybolt Universal seconds at 100 F. and a viscosity index of at least 80, about 1-4 percent by weight of oil-soluble calcium petroleum sulphonate having a minimum alkalinity equivalent to about -25 mg. of potassium hydroxide per gram of sulphonate as supplied, about .0250.25 percent by Weight of potassium acetate and about .0250.25 percent by weight potassium stearate, the ratio of potassium acetate to potassium stearate being from 5:95 to :5, whereby a stable emulsion is provided which effects minimum wear.

References Cited in the file of this patent UNITED STATES PATENTS 2,487,080 Swenson Nov. 8, 1949 2,820,007 Van der Minne et a1. Jan. 14, 1958 2,894,910 Francis et a1. July 14, 1959 2,927,079 Jcnse et al. Mar. 1, 1960 UNITED-ESTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,159,580 December 1, 1964 Irving P. Hammer et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Columns 5 ando, TABLE 1, "Example N0. 8", Opposite "Agerite Stalite", for "0.4" read 0.5 column 5, line 48, for "demonstarte" read demonstrate Signed and sealed this 4th day of May 1965.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

1. A COMPOSITION FOR USE AS HYDRAULIC FLUID CONSISTING ESSENTIALLY OF A WATER-IN-OIL EMULSION, THE WATER CONTENT OF SAID EMULSION, BEING ABOUT 10-50 PERCENT BY WEIGHT, THE OIL HAVING A VISCOSITY OF ABOUT 100-400 SAYBOLT UNIVERSAL SECONDS AT 100*F. AND A VISCOSITY INDEX OF AT LEAST 80, ABOUT .25-6.00 PERCENT BY WEIGHT OF OIL-SOLUBLE CALCIUM PETROLEUM SULPHONATE HAVING A MOLECULAR WEIGHT OF AT LEAST 975, THE CALCIUM PETROLEUM SULPHONATE HAVING A MINIMUM ALKALINITY EQUIVALENT TO ABOUT 20-25 MG. OF POTASSIUM HYDROXIDE PER GRAM OF SULPHONATE AS SUPPLIED, AND ABOUT 0.01 TO 1.0 PERCENT BY WEIGHT OF A POTASSIUM SALT OF A SATURATED STRAIGHT-CHAIN FATTY ACID HAVING A CARBON CHAIN LENGTH OF C2-C4, WHEREBY A STABLE EMULSON IS PROVIDED WHICH EFFECTS MINIMUM WEAR.
 3. A COMPOSITION FOR USE AS HYDRAULIC FLUID CONSISTING ESSENTIALLY OF A WATER-IN-OIL EMULSION, THE WATER CONTENT OF SAID EMULSION BEING ABOUT 10-50 PERCENT BY WEIGHT, THE OIL HAVING A VISCOSITY OF ABOUT 100-400 SAYBOLT UNIVERSAL SECONDS AT 100*F. AND A VISCOSITY INDEX OF AT LEAST 80, ABOUT 0.25-6.00 PERCENT BY WEIGHT OF OIL-SOLUBLE CALCIUM PETROLEUM SULPHONATE HAVING A MOLECULAR WEIGHT OF AT LEAST 975, THE CALCIUM PETROLEUM SULPHONATE HAVING A MINIMUM ALKALINITY EQUIVALENT TO ABOUT 20-25 MG. OF POTASSIUM HYDROXIDE PER GRAM OF SULPHONATE AS SUPPLIED, ABOUT 0.01 TO 1.0 PERCENT BY WEIGHT OF A POTASSIUM SALT OF A SATURATED STRAIGHT-CHAIN FATTY ACID HAVING A CARBON CHAIN LENGTH OF C2-C4, AND ABOUT 0.02-1.49 BY WEIGHT OF POTASSIUM STEARATE, THE RATIO OF THE POTASSIUM SALT OF THE C2-C4 SATURATED STRAIGHT-CHAIN FATTY ACID TO POTASSIUM STEARATE BEING FROM 5:95 TO 95:5, WHEREBY A STABLE EMULSION IS PROVIDED WHICH EFFECTS MINIMUM WEAR. 